Recording-hydrometer



D. s. HOLT.

RECORDING HYDROMETER.

APPLICATION FILED JULY 14.1919.

4 S S-SHEET l- INVENTOR ATTORNEYS.

D. S. HOLT.

RECORDING HYDROMETER.

APPLICATION FILED .IULY 14.1919.

1,341,014. Patented ay25',1920.

4 SHEETSSHEET 2- @W MM. ATI O R N EY$ D. S. HOLT.

. RECORDING'HYDROMETER.

- APPLICATION FILED JULY 14.1919.

-SHEET 3.

Patented May 4 SHEETS Wi w- ATTORNEYS.

D. S. HOLT.

RECORDING HYDROMETER." APPLICATION FILE-D JULY 14,1919.

1,341,014, Patented May 25,1920.-

4 SHEETSSHEET 4.

INVENTOR UNITED STATES PATENT OFFICE.

DANIEL S. HOLT, OF MITTINEAGUE, MASSACHUSETTS, ASSIGNOR TO STRATHMORE PAPER COMPANY, OF MITTINEAGUE, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

Specification of Letters Patent.

Patented May 25, 1920.

Application filed July 14, 1919. Serial No. 310,762.

To all whom it may concern have been provided heretofore and that various types of recording hydrometers will be found in the prior art. Such hydrometers however, are characterized in that the recording pen, or some actuating part thereof, is carried bythe hydrometer bulb itself,

' which necessarily requires special structure of the hydrometer and special calibration thereof, all of which I seek to avoid.

"According to one feature of this inveni'tion, provide a recording hydrometer, which makes use of a standard hydrometer' bulb, such bulb being norrrially free to float in the fluid being-tested, and which includes a record pen periodically movable to plot the hydrometer reading, the movement of the pen to plotting position being limited by the height of the hydrometer relative to the fluid being tested.

According to another feature of the invention, means are provided to periodically grip the hydrometer bulb and hold it against flotation while a member descends upon it and such member is arranged to move the recording pen.

According to another feature of-the invention, the movable member, which descends upon the hydrometer' bulb, is connected to the recording pen through the 1ntermediary of a thermometric mechanism, such for example as that employed in standard recording thermometers, and such mechanismis connected to the fluid being tested .to move the pen relatively to said member according to temperature variations in the fluid, whereby an automatic correction of the specific gravity readings for temperature variations-is obtained.

According to another feature of the invention, I employ a standard recording thermometer but mount'the active mechanism thereof on a member, which is periodically moved to a new position on the record sheet and is limited in such movement b the height of the hydrometer in the fluid.

According to another feature of the in vention, means are provided to cause a shifting of the recording pen, as just de scribed, and means are'provided 'to move the pen into and out of engagement with the record sheet at proper times and in coordinated relation with the shifting of the pen, so that the latter is held away from the sheet while it is being shifted.

According to a further feature of the in vention, means are provided to-automatically flush the hydrometer at periodic intervals.

Other features and advantages will appear in the following description and in the illustrative embodiment of the invention in the accompanying drawings, in which- Figure I is a front exterior elevational View of the complete apparatus;

Fig. 2 is a sectional elevational view thereof with the actuating mechanism removed Fig. 3 is a fragmentary cross-sectional view, taken on the line 33 of Fig. 2, and illustrates the mechanism for moving the pen to and from its record sheet;

Fig. 4c is an enlarged sectional View of a part of Fig. 3;

Fig. 5 is a fragmentary plan view, taken on the line 55 of Fig. 2, and illustrates the mechanism for operating the control valve for the hydrometer flushing device;

Fig. *6 is a sectional plan View, taken on the line 6--6 of Fig. 2, and illustrates the sample can for the fluid to be tested;

Fig. 7 is a perspective view illustrative of the hydrometer clamping device;

Fig. 7 is a perspective view illustrative of a detail shown in Fig. 2;

Fig. 8 is an enlarged front elevational view of the actuating mechanism shown in Fig. 1; 1

. Fig. 9 is a rear elevational view thereof;

Fig. 10 is a fragmentary perspective view of the escapement wheel of the actuating Fig. 12 is a fragmentary sectional plan View taken on the line 12-12 of Fig. 11; Fig. 13 is a fragmentary perspective view illustrative of a detail of the actuating mechanism;

Fig. 1 1 is an elevational view of the actuating mechanism for the flushing water" control valve;

Fig. 15 is an elevational view of the actuating mechanism for the hydrometer clamping device;

Fig. 16 is an enlarged fragmentary sectional view of a part of Fig. 15;

Fig. 17 is an elevational view of the cam for shifting the pen arm to and from the position for recording the hydrometer readings;

Fig. 18 is an elevational view of the mech? anism for moving the pen into and out of engagement with the record sheet; and

Fig. 19 is a plan view of a part of Fig. 18;

Fig. 20 is a diagrammatical view illustrative of the electrical connections of the apparatus.

Theapparatus, in general, comprises, a movable record sheet; a temperature recording mechanism to operate on such sheet;

a sample can to receive the fluid whose temperature and specific gravity is to be measured and recorded; a hydrometer; clamping mechanism operable periodically to grip the hydrometer and frictionally hold it in whatever position it may be; mechanism to shift the temperature recording mechanism as a unit'to a different position on the record sheet so that the temperature recording pen may likewise plot the specific gravity reading, the shifting of the temperature recording mechanism being limited by means engageable with the clamped hydrometer for this purpose; mechanism associated with the shifting mechanism to move the recording pen away from the record sheet prior to the shifting movement in one direction and into engagement with the sheet at one end of such movement and to reverse such operations 'for the shifting movement in the opposite direction; mechanism to flush the hydrometer after each reading has been taken; and actuating mechanism to periodically operate the various mechanisms described and coordinate them one with another.

Referring to Fig. 1; A represents the casing of the apparatus, which is of rectangular box-like form and receives Within it most of the various unit mechanisms described. The front face of casing A is largely closed in by upper and lower cover plates B and C, respectively, which plates are readily removable to permit access to the interiormechanism.

The movable record sheet is of usual form. As shown, it consists of a circular sheet 8, suitably held to a disk (5, which is revoluble about the axis a by suitable mechanism, such as clockwork, which may be supported on the rear face of cover plate B. In this instance, the'driving means for sheet .9 is an electric clock, which is controlled electrically from a master clockin a manner well understood in the art. Detailed illustration and description of the driving means for sheets is thought unnecessary to an un derstanding of the invention and it will suffice to state that sheets is so moved that the generally radial ordinates 0 on sheet .9 will represent time.

The temperature recording mechanism is also of-known and usual form. It is indicated generally and conventionally by T, and p is the recording pen, 1 the arm carrying pen 7?; t the tube connectingmechanism to the thermometric bulb b whichis disposed unnecessary to an understanding of the in vention and for a more complete disclosure reference is made to U. S. Letters Patent No.

659,615, granted October 9, 1900, to William H. Bristol.

The sample can 20, (Fig. 2) is merely a cylindrical sleeve closed at its base by a cored member 21, by means of which it is supported from the base of casing A. A

passage 22 in member 21 is connected at one end with aninlet pipe 23 and opens at the other end into the base of the sample can 20. A plate 2 1, preferably with a serrated periphery (Fig. 6), is supported from and in spaced relation'with the member 21 and with the samplecan, to overlie the inlet passage 22 and prevent the incoming fluid from disturbing the fluid thereabove and the consequent interference with the hydrometer readings. Surrounding the sample can and likewise supported on member 21 is an overflow tank 25, the base of which communicates, byway of a passage 26 in member 21 with an outlet pipe 27. The fluid to be measured is continuously supplied to the bottom of the sample can 20 and overflows from the top thereof into tank 25.

The hydrometer, of usual commercial form, is represented conventionally at h in Fig. 2. It normally floats freely in the fluid contained in sample can 20 and is guided against lateral displacement between a finger 29 and upper and lower fingers 28. All the fingers are bent'up from wire, the finger 29 being straight. and the fingers 28 being bent to afford a recess 30 through which the hydrometer may ordinarily freely move.

end of rod 32 is rotatably mounted in a bearing 33 on the rear wall of easing A and carries an arm 34, the free end of which is connected by a horizontal link 35 to a lever 36 pivoted at 37 to a bracket on the rear wall of casing A. The outer end of lever 36 is weighted, as at 38, and the connection of link 35 to lever 36 is closely adjacentthe fulcrum 37 in order to provide sufiicient leverage so that a falling movement of the weighted lever 36 will turn rod 32 and finger 29' to firmly clamp the 'hydrometer h against fingers 28. The lever 36 is normally held in its upper position by a rod 39, which connects it to a unit of the actuating mechanism to be later described. At the proper time rod 39 is released to allow the. lever 36 to descend and cause the clamping of the hydrometer and later is lifted by a suitable cam into the illustrated position.

The entire thermometric mechanism T is carried by a frame 40, which is fixed to a horizontal shaft 41 (Fig. 3) oscillatable in a bracket 42 secured to a horizontal cross bar 43 in the casing A. Fixedto shaft 41 is an arm 44 which is connected near shaft 41 by an upwardly extending rod 45 to a second unit of the actuating mechanism to be described. Such unit normally holds arm 44' inits upper position, as illustrated, but peri 7 The rod 48 depends from bar 46 and passes loosely, through a loop 49 on. the described rod '32 for guiding purposes. On the lower end of rod 49 is a conical cap-like member 50 and such member is approximately vertically in line with the upper end of hydrometer it so that upon a release of arm 44 some part of the cap 50 will engage the upper end of the hydrometer. The conical nature of'the cap provides for self-centering of the cap on'the top of the hydrometer. The hydrometer-is clamped, as already described, before the cap 50 is permitted to descend, so that the hydrometer acts as a stop to limit the degree of tilting of frame 40 by arresting the descent of eap 50. p I

It will thus be seen that the recording pen 7) may be shifted on sheet 8 fromthe position in which it is effective to plot the temperature curve 00 to a second position in which it is effective to plot the specific gravity readings y. Since the position in which pen p comes to rest at the end of the shifting can 20' (which fluid is obviously kept at constant level), the marks y made on sheet 8 are proportional to the specific gravity of such fluid and may by suitable calibration be made to read directly in any desired units of specific gravity, such as degrees Baum for example. Since it seldom happens that any two hydrometers it will be exactly alike, he adjustable connection of rod 48 to arm 44 is provided so that upon the substitution of a new hydrometer, the degree of tilting of pen [2 may be adjusted until the specific rgravity graduations on sheet 8 correctly indicate the position of hydrometer h in the sample can 20.

The fact that the pen used to plot the hydrometer readings is connected to frame 40 through the intermediary of a thermometric mechanism, whether or not such mechanism is used to plot a temperature curve 00, makes possible an automatic correction of the hydrometer readings for variation in temperature of the fluid being tested. so that true specific gravity readings are plotted on the record sheet 8. Assume, for example, that 60 degrees Fahrenheit is the temperature at which the indications on the hydrometer correctly indicate the specific gravity of the fluid, then if the temperature exceeds this figure, the pen p will be moved proportionately, and relatively-to frame 40, radially outward on the record sheet .9 so that when the frame 40 is later moved inwardly to plot the hydrometer reading the pen 0 will not be moved so far as it otherwise would be. Conversely, if the temperature is below the standard temperature, the pen will be moved by mechanism t radially inwardly, so that on shifting of the frame 40 to its inner position pen 29 will be moved radially inwardly farther than it would be by the shifting mechanism alone. Thus, the hydrometer readings are automatically corrected for temperature and true corrected readings only are plotted on the record sheet 8. The length of the pen arm 1 is made of such length and the temperature and specific graduations on sheet 8 are so proportioned that the radial movement of pen pby the thermometric mechanism If correctly indicates on the specific gravity chart the proper correction of the specific gravity readings for temperature.

Since the pen 7 is periodically shifted from temperature to specific gravity plotting position, it is necessary to move the pen 12 away from sheet 8 prior to each shifting movement of frame 40 in each direction and to then move it'into engagement with the sheet 8 after the end of each shifting niovepen arm 1, therefore, has considerable spring and it is such spring, in this instance, which holds pen 1!) against .the record sheet 8,

- Mounted to slide horizontally in frame reading is taken.

are two parallel wires 51, which are connected at their forward ends by a cross bar 52, so positioned as to engage the arm 7" on outward movement and cause pen p to be moved out of contact with .sheet 8. The inner ends of wires 51 are likewise connected together by an integral cross bar 53 which abuts a lever 54 pivoted at its upper end to frame 40. A-bow spring 55, disposed between the frame 40 and cross bar 53 normally holds the latter and lever 54 in the illustrated position andallows the pen to bear against the sheet 8 under the spring action in arm 1". The lower end of lever is movable in a radial recess 56 in the described shaft 41 and axially 'slidable in the latter is a rod 57, one end of which is capable of engaging and moving lever 54 against the force of spring 55. The other end of rod 57 projects beyond the rear end of shaft 41 (Fig. 3) and may be engaged and moved by one arm of a bellcrank lever 58, which is pivoted to a bracket on the rear wall of easing A. The other arm of lever 58 is connected by an upwardly extending wire 59 to a unit of the actuating mechanism to be later described. On a lifting of wire 59 pen [9 will be moved away from the sheet 8 and on a subsequent lowering of wire 59, pen 10 will again be allowed to engage the sheet. The movement of pen 3) to and from the record sheet are coiirdinated with the shifting movement of frame 40 by the actuating mechanism, as will later appear.

It is essential, in certain instances, to wash the hydrometer after each reading. Thus, when the fluid in sample can 20 is sticky size, considerable of this size would adhere to the hydrometer h and weight it down, so asto seriously affect the accuracy of the hydrometer readings. Where fluid of this or like nature, is used, I provide means for flushing the hydrometer after each reading has been taken This periodically cleans the hydrometer and main.- tains it free from undesired accumulations. By flushing the hydrometer after the reading has been plotted on sheet 8, the accuracy of the plotted reading is unaffected and the subsequent dilution of the fluid in the sample can by the flushing water causes no difficulty, for the diluted fluid is displaced by fresh undiluted fluid before the next For flushing the hydrometer h,,a tank 60 is provided on casingA and supplied with water by an inlet pipe 61 (F ig. 2). Such tank is connected by a pipe 62 to a vane or nozzle 63 which directs the flushing water against the hydrometer as illustrated. The flow of flushing water from tank 60 is con trolled by. a weighted gravity-operated valve 64, which normally closes the outlet of tank 60.. Valve 64 has an upwardly extendand thus the rack bar.

ing stem 65, which is connected to a lever 66 (Figs. 2 and 5) fixed on a shaft 67 mounted in a bracket on casing A. Also fixed to shaft 67 is a second lever 68, which is connected by a wire 69 to another unit of the actuating mechanism, which periodically opens and closes valve 64 in properly timed relation with the other elements of the apparatus, as will appear.

The actuating mechanism for the various elements heretofore described, includes, as motive power, a clock spring 70 (Fig. 8) and a suitable gear train 71, whereby a shaft 72 may be turned in the direction of the arrow from spring 70. A gear train 73 is provided for connection to a suitable governor in a manner now too well understood in the art to require detailed description or illustration herein. The rotation of the shaft 72 under the action of spring 70 is controlled by an escapement mechanism, which is operated electromagnetically in timed relation with the record sheet 8. Thus, as diagrammatically shown in Fig. 20, E represents an electric clock, of any suitable type, which is arranged to propel the record sheet 8. Clock E is electrically connected in series, by wires 74, with a master clock M, a battery 75, and an electromagnet 76. The master clock M causes the clock E to be operated in synchronism with it, in a now well known manner, and causes the record sheet 8 to be moved at a definite time rate. In this instance, the clock E is energized once each minute and thus the record sheet 8 is moved step-by-step by angular movements each of which represents one minute. The electromagnet 76 will obviously be energized once each minute.

The escapement includes an escapement segment 77 mounted to turn on a stud 78 and connected to a gear 79 to turn therewith. in mesh with gear 79 is a rack 80 which is slidably supported in the frame F of the actuating mechanism. The rack 80 is slotted, as shown in Fig. 9, to receive an arm 81 pivoted at 82 to frame F. Such arm has an integral and laterally offset extension 83 the upper end of which lies closely adj a cent the gear 73 of the gear train 73 described and in the path of pin 84 thereon. A spring 85 tends to move rack 80 to the right, as viewed in Fig. 9, while the clock spring 70 tends to move it to the left, by reason of the pin 84 engaging the arm 83 The spring 85 is relatively light and is intended merely to move the gear 79 and segment 77 in a clock wise direction after the pin 84 and arm 83 have been disengaged, as will appear. Therefore, the clock spring 70 will readily overcome spring 85 and will tend to turn segment 77 in a counter clockwise direction. The escapementsegment has a series, as ten,

radial teeth 86 and between such teeth are laterally projecting teeth 87. A springarm 88, fixed at one end to frame F, carrles a the segment 77. The latter, however, is soon arrested by a projection 90 on arm 88, which projection engages a lateral tooth 87 of the segment and holds it until arm 88 is allowed to spring back into the illustrated position. At such time, tooth 87 will pass freely through a slot 91 in projection 90 and allow the segment 77 to move until the next tooth 86 is arrested by latch 89. It will thus be seen that shaft 72 may be turned by a series, as ten, small intervals, these intervals being so small that the pin 84 does not become disengaged from arm 83. At the end of the tenth interval, however, the end of the segmerit 77 has been reached andthe latch 89 can no longer hold the latter. The release of the segment 77 permits rotation of gear 7 3 and thus the segment is turned by pin 84 until the latter becomes disengaged from arm 83. As soon as this happens, spring 85, being now unopposed by the clock spring 70, immediately returns the segment 77 into position for a subsequent cycle of operation, the extent of this return movement being limited by the engagement of shoulder 92 on rack 80 with the stop 93. Immediately that pin 84 is free from arm 83, shaft 72 turns through the remainder of the revolution, under speed controlled by a governor, as above mentioned, being eventually arrested by arm 83 which meanwhile has been brought back into proper position by spring 85. Thus, oncein each definite time interval, as ten minutes, shaft 72 completes one revolution and, during this interval, makes a series, as ten, very small increments, which do not, except in one instance, as will later be explained, function with the hydrometer apparatus but are suffered since by so doing it is insured that the record sheet 8 and the actuating units operated by shaft 72' will work in synchronism.

The unit for 'a'ctuatingthe hydrometer gripping device will next be described with reference to Fig. 15.

'94 has dwell. portions 98 and 99, a sharp let off portion 100 and afris'e portion 101. At

the start of each cycle, roll 96 engages the. dwell portion 98, thereby holding arm 95 I This unit consists of a cam 94, fixed on the shaft 72, and a lever lifted and preventing the weighted lever 36 y from operating the hydrometer gripping dev1ce. At the end of'the tenminute interval described, the roll 96 has left dwell 98 and only the knife edge 97 holds lever 95 in raised position. Consequently upon the start of the large step of movement of shaft 72 (which as has been noted is very nearly one revolution) the knife edge 97 will drop sharply ofl the dwell 98 and drop upon the dwell 99, thereby permitting the lever 36 to operate the hydrometer gripping device. The roller 96 will then traverse the dwell 99' for an interval long enough to permit the plotting of the hydrometer reading and will eventually engage the rise 101, whereby the lever 95 will be raised and the hydrometer released from its clamping device by the consequent raising-of lever '36.

' The unit of the actuating mechanism for controlling the mechanism for moving the pen 3? to and from the record sheet 8 will next be described with particular reference to Fig. 18. Two cams'102 and 103 are fixed to the drive shaft 72. A lever 104, mounted on the cross bar 96, carries on its free end a roll to engage cam 103' Pivoted intermediate its ends to lever 104 at 105 is a lever 106 the free end of which is engageable with the cam 102. Lever 106 is held to its cam 102 by a weight 107 (Figs. 2 and 8) suspended by a wire 108. The rear end of lever 106 is curved .on a radius equal to that of the hub 109 oflever 104 and such hub is recessed, as

at 110 so that the curved end of lever 106 ,on the curved end of lever 106 and a wire 59 already described, connects the latter to the lever 58. When thelever 111 is lifted above the periphery of hub 109, the pen p is moved away from sheet 8, as already described, but when the curved end of lever 106 lies concentric with hub 109, the pen p engages the record sheet. It should be noted that when both levers 104 and 106 are moved equally and simultaneously, no movement of lever 111 takes place and in order to actuate the latter, a relative movement must take place between the levers' During the .several small steps of movement of shaft 72, both levers 104 and 106 are gradually rising equally for the surfacesof both coincide from points .112 to 113. At or about the start of the large step of movement of shaft 7 2, the points 113 of the cams are engaged by the levers. As soon as this step of movement takes place, lever 105 will be allowed to drop, as cam 102 travels from points 113 to 114 while lever 104 will be maintained in lifted position for some time, viz., until it reaches point 115. Therefore, the lever 111 will be raised shortly after the shaft 72 commences its large step ofmovement and thereby the pen 10 will be moved away from sheet 8. Thereafter, both levers remain stationary but at different levels, so that pen p is held away from sheet 8 during the shifting of frame 40. After such shifting of frame 40 has been completed, the lever 104 has reached point 115 and thereafter quickly drops to point 116 and to the same level as lever 1.06. Thus lever 111 is lowered and pen allowed to engage .sheet 8..

Shortly after lever 104 has dropped, as described, lever 106 drops from points 117 and 118 and thereby raises lever 111 and causes pen to be moved away from the sheet 8. This latter movement of course,occurs before the return movement of frame 40. Thereafter, both levers remain stationary but at different levels to hold pen 10' away from the sheet .9 until the completion of the return movement of frame 40. At such time lever 106 has reached point 119 and is gradually raised from points 119 to 112, thereby allowing pen 7) to be moved into engagement with the record sheet.

-The unit of the actuating mechanism for causing the shifting of frame40 will next be described with particular reference to Fig. 17. Such 'unit includes a cam 120 fixed on shaft 72 and a lever 121 pivotally mounted on the cross rod 96. 'Lever 121 is connected to the described wire 45 which holds the shifting lever 44 from movement under the action of gravity. During the many short steps of movement of shaft 72, and for a suf ficient time thereafter to permit the pen 3) to be moved away from sheet 8, as described, lever 121 engages a dwell surface 122 on cam 120. After pen p has been disengaged from sheet 8, lever 121 drops along the surface 123 until it strikes a dwell surface 124, whereby lever 40 is allowed to drop until arrested by the hydrometer h, it being understood that the drop of lever 44, permitted by earn 120., is greater than the greatest movement of the lever ordinarily necessary to cause cap 50 to engage the hydrometer. After the frame 40 has been shifted, the le ver 121 rides on the dwell surface 124 until the pen 1) is moved into and again moved out of engagement with sheet 8, whereupon lever 121 encounters the rising surface 125 and gradually lifts the lever 44 until in the illustrated position.

In connection with the shifting of hydrometer h, it should be noted that the weight of the lever 44 effective to cause the cap 50 to lower into engagement with hydrometer k, may be regulated by means of a counterweight 126 adjustably mounted on an arm 127 fixed to shaft 141, as shown in Fig. 2.

The unit of the actuating mechanism for operating the flushing water valve 64, will next be described with particular reference to Fig. 14. "Such unit includes a cam 128,

fixed to shaft 72 and two levers 129 and 130. Levers 129 and 130 are pivoted together, scissors like fashion, at 131 and lever 129 is pivotally supported on rod 96 while lever 130 has a curved end portion adapted to fit into a recess on the hub of lever 129 in a manner analogous to that described in connection with the structure shown in Fig. 18. A lever 132 is pivoted, similarly to lever 111, and has its free end riding on the curved end of lever 131. The described wire 69 is connected to lever 132. A weight 133 is suspended by a wire 134 from lever 130 and functions to lift lever 132 when permitted to do so by the cam. Both levers ride on the periphery of the one cam 128, the lever 130 engaging in advance of lever 129. At the start of the cycle of operations, the cam 128 is positioned as shown in Fig. 14. That is the lever 130 has dropped while lever 129, being slightly in the rear of lever 130, is still in lifted position. Thus, lever 132 is lifted and the flushing water valve 64 is open. At the end of the first small step of movement of cam 128, which occurs substantially one minute after the lever 130 drops, lever 129 is permitted to quickly drop, which by lowering the pivot 131 causes the curved end portion of lever 130 to lie in the recess of the hub of lever 129. Thus lever 132 is allowedto drop and thereby close the valve 64. Thereafter, both levers are carried along at equal levels, both being first gradually raised on the portion 135, then held raised by the dwell portion 136 until the end of the large step of move ment of cam 128, at which time lever 130 drops to lift lever 132 and open valve 64. Thus, the valve is opened at the very end of each cycle of operation and held open until the start of the next cycle.

The various units of the actuating mechanism and in fact all actuating elements of the entire apparatus are characterized in that they are operated by a motor of very small power. That is the clock spring 20 not sufficiently powerful to produce the sudden movements of the various parts. Consequently, throughout the apparatus, all sharp sudden movements are produced by allowing weighted parts to drop. The relarious mechanisms described and I do not therefore intend to, limit my invention thereto, although the particular actuating mechanism described is important for the reasons pointed out.

A most important feature of the invention'consists in the arrangement, whereby a standard hydrometer bul b can be used, due tothe provision for intermittent engagement with the hydrometer of parts of the recording apparatus, thus eliminating the necessity for attaching parts to the hydrometer or for special construction 'of the latter. This arrangement permits the ready substitution of new bulbs, to replace broken ones without the inconvenience and delay necessarily incident to obtainingbulbs of special construction. Moreover, the. arrangement 'permits bulbs with the standard graduations to be used, thus doing away with the necessity for special calibration.

Another feature of importance consists in the utilization of a standard recording thermometer, 'with the provisions described for making the temperature plotting pen also,

plot'the specific gravity readings, In this connection, it is to be noted that while it is desirable and preferred to provide for plotting both temperature and specific gravity, it is not accordingto all features of the invention, for the interposition of the thermometric mechanism, as described, has an important function, whether or not the temperature readings are plotted, for it pro vides for automatic correction of the specific gravity readings.

The inventiop has beendisclosed herein, in an embodiment at. present preferred, for illustrative purposes but the scope of the invention is defined by the appended claims rather than by the foregoing description.

' a container to-receive the fluid to be tested,

What I claim is- 1. Inan apparatus of the class described,

a container to receive the fluid to' be tested, a hydrometer therein, a movable record sheet, a recording stylus to record the hydrometer readings on such sheet, a movable member, a thermometric mechanism interposed between said stylus and member and operative by variations of the temperature of the fluid to move said-stylus relatively to said member, and means operable periodically t ove saidmember into engagement with the hydrometer;

2. In an apparatus of the class'described,

a hydrometer therein, movable means periodically engageable with the hydrometer"- andlimited in its movement by the height of the hydrometer in the fluid, a thermometric mechanism carried by said' means,

and an indicator arm carriedby said means and movable by said mechanism independently of the movement of said means."

- 3. In 'an apparatus of the class described,

a container'to receive the fluid to be tested, a hydrometer therein, means to periodically grip the hydrometer and hold it in the variand means operable periodically to move said member into engagement with the gripped hydrometer. p

. 4. In an apparatusof the class described, a container to receive the fluid to be tested, a hydrometer therein, means to periodically hold the hydrometer against movement by the buoyant action of said fluid, a member movable periodically to engage the gripped hydrometer and limited in its movement thereby, a thermometric mechanism carried by said member, and an indicator arm carried by said member and movable by said mechanism independently of the movement of said member.

5. The combination with a recording thermometer, of a member carrying the thermometric mechanism thereof and the stylus arm, a container for fluid whose temperature and specific gravity are to be recorded, means connecting said mechanism to said container so that temperature variations of the fluid "may be recorded on the movable record sheet of the thermometer, a hydrometer in said container, means to periodically hold it agains'tmovement by the buoyant action of said fluid, means to move said member, and means associated with the 105 sition on the record sheet, the degree ofshifting movement being limited by the height of the hydrometer relative to the' fluid in said container.

7. The combination with a recording thermometer, includingthe stylus arm, the movable record sheet, and the actuating mechanism for such arm, of a container for fluid, means connecting the latter to said mechanism, a, hydrometer in said container, means to periodically move said mechanism and its associated arm along the record sheet,

the degree of movement of said mechanism being limited by the height of the hydrometer relative to the fluid in said container, and means to move the arm away from the record sheet prior to such movement and toward the record sheet after such movement.

8. The combination with a recording thermometer, including the stylus arm, the movable record sheet, and the actuating mechanism for such arm, of a container for fluid, means connecting the latter to said mechanism, a hydrometer in said container,

means to periodically move the said mechanism and its associated mechanism laterally of the record sheet to a position for plotting the hydrometer readings and back again to the position for plotting the temperature readings, means associated with the last named means to engage thehydrometer and limit the extent of the first named movement, and mechanism to move the arm toward and away from the record sheet operable to move the arm toward the sheet at the end of the movement of the arm in each direction" and to move the arm away from the sheet prior to the start of the movement of the arm in each direction. a

9. In an apparatus of the class described, a container to receive the fluid to be tested, a hydrometer therein means to periodically hold the hydrometer against movement by the buoyant action of said fluid, a member movable periodically to engage the gripped hydrometer and limited in its movement thereby, a thermometric mechanism carried by said member, and an indicator arm movable by said mechanism independently of the movement of said member, said member being subsequently movable away from the hydrometer, and means to move said arm toward the record sheet at the end'of the first named movement and away from the sheet prior to the last named movement.

10. In an apparatus of the class described, a container to receive the fluid to be tested, a hydrometer normally free to float therein, an indicator arm, means to periodically move said arm, and a member associated and movable therewith and arranged to engage the hydrometer, whereby the position of the moved arm indicates the relative height of the hydrometer in the fluid in said container.

11. In an apparatus of the class described, a container to receive the fluid to be tested, a hydrometer normally free to float therein,

'an indicator arm, means to periodically move said arm, a member associated and T movable therewith andarranged to engage the hydrometer, whereby the position of the moved arm indicates the relative height of the hydrometer in the fluid in said container, and means to automatically wash the hydrometer after each engagement of said member therewith, o

12. In an apparatus of the class described,

a container to receive the fluid'to be tested, 1

a hydrometer normally free to float therein, means to periodically grip the hydrometer and hold it against flotation, a movable indicating arm, a member movable therewith,

.and adapted to engage the gripped hyand hold it against flotation, a movable indicating arm, a member movable therewith and adapted to engage the gripped hydrometer as a stop, means to periodically move said member into and out of engage ment with the hydrometer, and means to automatically wash the latter after each engagement of said member therewith.

14. In an apparatus of the class described, a container to receive the fluid to be tested, a hydrometer normally free to float therein, means to periodically grip the hydrometer and hold it against flotation, a movable indicating arm, a member movable therewith and adapted to engage the gripped. hydrometer as a stop, said member being movable by gravity into engagement with the hydrometer, means normally holding member away from the hydrometer, and means to periodically release the last named means.

15. A recording hydrometer, comprising, a movable record sheet, a recording pen to cooperate therewith, a container for the fluid, a hydrometer normally free to float therein, means to periodically grip the hydrometer and hold it against flotation, a member carrying said pen, means normally holding said member in one position, the member when released being movable by gravity and limited in such movement by the gripped hydrometer, and means movable synchronously with the record sheet to periodically actuate the gripping means and release the holding means.

16. In an apparatus of the class described, a movable record sheet, a recording pen to cooperate therewith, a container for fluid, a hydrometer normally free to float therein, means movable by gravity to grip the hydrometer against movement by flotation, means to hold the gripping means against movement by gravity, a member carrying the pen, means normally holding said member in one position, said member being movable when released by gravity and limited in such movement by the gripped hydrometer, a-springmotor, and means driven thereby .to suddenly release said gripping means and 17'. In an apparatus of the class described, a container for fluid, a hydrometer normally free to float therein, means to periodically grip the hydrometer, a member periodically movable into engagement with the latter, a movable record sheet, a pen to cooperate with the latter and movable by said member, means to flush the hydrometer after each operation of the gripping means, said flushing means including a control valve; a cam shaft; cams thereon to control the operation of said gripping means, the movement of said member, and the operation of said control valve; and means to periodically move said shaft through one complete cycle; whereby the hydrometer is gripped, the pen moved, and the control valve opened to flush the hydrometer, one of said cams arranged to hold said valve-open at the end of said cycle, and means operable at a predetermined time after the end of said cycle to move such cam sufliciently to release said valve and allow it to close. x

18. In an apparatus of the class described, a container for fluid, a hydrometer normally free to float therein, means to periodically grip the hydrometer, a member'periodically movable into engagement with the latter, a movable record sheet, a pen to cooperate with the latter and movable by said member, means to flush the hydrometer after each operation of the gripping means, a cam shaft, cams thereon to control the operation of said gripping and flushing means and the movement of said member, and means to periodically move said shaft through one complete cycle; whereby the hydrometer is gripped, the pen moved and the flushing means operated I to flush the hydrometer. I 19. In an apparatus of the class described, a container for the fluid to be tested, a hydrometer normally free to float therein, a movable indicator arm, a member associated therewith and adapted to be engaged by the hydrometer on relative movement of the latter and said member toward one another, and means associated with said member to move the hydrometer laterally in the container upon such relative movement into alinement with said member.

20. In an apparatus of the class described, a container for the fluid to be tested, a hydrometer normally free to float therein, a movable indicator arm, and a hollow cone shaped member associated therewith and arranged to receive the upper end of the hydrometer within it and force said end laterally into its apex.

21. In an apparatus of the class described, a container for the fluid to be tested, a hydrometer normally free to float therein, means to periodically hold the hydrometer against flotation, and means movable into engagement with the gripped hydrometer to indicate the relative height of the latter in said fluid.

22. In an apparatus of the class described, a container for the fluid to be tested, a hydrometer normally free to float therein, means to periodically hold the hydrometer against flotation, said holding means when released forming guides to confine the hydrometer within limits against lateral movement in the container.

DANIEL S. HOLT. 

